认知无线网络基于正交频分复用的子载波和功率分配策略

Novel strategy for subcarrier and power allocation in OFDM-based cognitive radio networks

为满足认知用户对主用户的干扰约束,建立了在主用户接收端干扰受限条件下最大化认知用户容量的数学优化问题;进一步提出了当主用户信噪比不断变化时,认知用户可根据干扰控制因子自适应地调整发射功率,最大化认知系统容量;利用拉格朗日乘数法,得到了该数学问题的最优解;最后,在多用户情况下提出了一种公平性和容量性能折衷的子载波和功率分配方案。仿真结果表明,在主用户可容忍的干扰约束下,该方案能有效地保证认知用户间的公平性且系统容量性能趋于最优。

In order to limit the interference caused by cognitive user within the range that primary users can tolerate. The mathematical optimization problem is formulated maximizing cognitive user’s capacity under the interference constraint at the primary receiver.When the signal-to-noise ratio of primary user changes according to the communication environment, the cognitive user can adaptively adjust its transmission power according to the interference control factor η. The optimal so1ution to the problem is obtained by utilizing the Lagrange method.A subcarrier and power allocation scheme are proposedamong multiple cognitive users, which is the performance tradeoff between fairness and system capacity. Simulation results show that the proposed scheme can efficiently guarantee the fairness of cognitive users and the capacity performance is close to the optimum.